This invention relates to the field of frustrated total internal reflection devices and more particularly to a frustrated total internal reflection switch using waveguides.
Fiber-optic communication systems include optical components, such as optical fibers coupled to switching components, that receive, transmit, and otherwise process information in optical signals. The switching components in a fiber-optic communication system selectively direct the information carried by the optical signal to one or more other optical components. A problem with optical switches for existing fiber-optic communication systems is that they require many complex optical components to perform the switching function. This adds to the cost and size of the fiber-optic communication system. It also leads to slower switching speeds and difficulties with aligning the switching components.
A frustrated total internal reflection switch using waveguides is provided that substantially eliminates or reduces disadvantages and problems associated with previous optical switches.
In accordance with one embodiment of the present invention, an optical switch for processing an optical signal includes an input waveguide having a reflective surface, a first output waveguide coupled to the input waveguide, and a second output waveguide. The second output waveguide has a first position spaced apart from the reflective surface of the input waveguide such that the reflective surface totally internally reflects an optical signal toward the first output waveguide. The second output waveguide also has a second position in proximal contact with the reflective surface to frustrate the total internal reflection of the optical signal such that the second output waveguide receives the optical signal.
Another embodiment of the present invention is a method for processing an optical signal that includes communicating an optical signal in a first waveguide and totally internally reflecting the optical signal at a reflective surface of the first waveguide toward a second waveguide. The method continues by placing a third waveguide in proximal contact with the first waveguide to frustrate the total internal reflection of the optical signal. The method concludes by receiving the optical signal in the third waveguide.
Yet another embodiment of the present invention is an optical switch for processing an optical signal that includes an input waveguide having a reflective surface, a first output waveguide coupled to the input waveguide, a second output waveguide, and a switching waveguide. The switching waveguide has a first position spaced apart from the reflective surface of the input waveguide such that the reflective surface totally internally reflects an optical signal toward the first output waveguide. The switching waveguide also has a second position in proximal contact with the reflective surface to frustrate the total internal reflection of the optical signal such that the switching waveguide communicates the optical signal toward the second output waveguide.
Technical advantages of the present invention include a frustrated total internal reflection optical switch that switches one or more optical signals using waveguides. By using waveguides to guide an optical signal to the switching region and to perform the switching operation, the present invention eliminates the need for costly and sometimes complex optical components. This results in a smaller packing density for the optical switch of the present invention and a more efficient, faster switching operation.
While in a switched state, the contact surface of a waveguide is typically placed in proximal contact with a reflective surface of another waveguide to frustrate the total internal reflection of the optical signal. A small portion of the optical signal may be reflected, however, at the reflective surface and processed as though the switch is operating in the unswitched state. This undesired result is one source of a crosstalk signal in the system.
Another technical advantage provided by the present invention is that the optical switch reduces the effects of a crosstalk signal generated by the above-identified reflection. In particular, the optical switch of the present invention processes any crosstalk signals so that a large portion of a crosstalk signal is not received by an optical component of the optical switch. The negative effects of a crosstalk signal are thereby reduced.
For example, in the switched state, an undesired crosstalk signal resulting from residual reflection at the FTIR interface between a reflective surface and a contact surface is further processed by a return-loop waveguide to reduce the crosstalk signal intensity. In particular, the crosstalk signal radiation is conveyed by the return-loop waveguide to a second FTIR interface within the output waveguide signal path. In the switched state this second FTIR waveguide interface frustrates the total internal reflection of the crosstalk signal at the reflective surface of the output waveguide. As a result, the small, undesired residual portion of the original optical signal undergoes further reduction in its intensity at this second FTIR interface. Therefore, only a negligible portion of the original optical signal, if any, comprises a crosstalk signal that may actually reach an optical component of the switch. Thus, the crosstalk signal is dissipated and its effects become negligible. The reduction in the magnitude of the crosstalk signal in the present invention will be referred to as a crosstalk improvement.
Another important advantage of the optical switch relates to the crosstalk improvement described above. Generally, the crosstalk signal described above is generated as a result of imperfections in the components of the optical switch, such as imperfections in the reflective and contact surfaces of the waveguides, or in less than ideal actuator performance which results in a slight air gap at the interface between the reflective and contact surfaces of the waveguides. By reducing the magnitude of crosstalk signals to acceptable levels during the operation of the optical switch using the return-loop waveguide, as described above, manufacturing tolerances for the components used in the switch may be increased, and components are thus easier and less costly to manufacture. For example, the reflective and contact surfaces of the waveguides may be constructed with increased surface roughness and still meet industry standards in minimizing crosstalk. Also, components having a greater degree of environmental contamination can be used, and still provide acceptable crosstalk performance during the operation of the switch.
In addition to supporting increased manufacturing tolerances for optical components, the use of the return-loop waveguides of the present invention allows actuator performance requirements to be relaxed. For example, the degree of proximal contact to which the actuator brings the reflective and contact surfaces of the waveguides may be relaxed and still provide acceptable crosstalk performance during the operation of the switch.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.